A variety of diseases exist that require regular treatment by injection of a medicament and such injections can be performed by using injection devices. Various injection devices for delivering injections of medicament are known in the art. Another type of injection pump that is gaining traction is the bolus injector device. Some bolus injector devices are intended to be used with relatively large volumes of medicament, typically at least 1 ml and maybe a few ml. Injection of such large volumes of medicament can take some minutes or even hours. Such high capacity bolus injector devices can be called large volume devices (LVDs). Generally, such devices are operated by the patients themselves, although they may also be operated by medical personnel.
To use an injector device, such as an LVD, it is first supported on a suitable injection site on a patient's skin. Once installed, injection is initiated by the patient or another person (user). Typically, the initiation is effected by the user operating an electrical switch, which causes a controller to operate the device. Operation includes firstly injecting a needle into the user and then causing the injection of medicament into the user's tissue. Biological medicaments are being increasingly developed which comprise higher viscosity injectable liquids and which are to be administered in larger volumes than long-known liquid medicaments. LVDs for administering such biological medicaments may comprise a pre-filled disposable drug delivery device or, alternatively, a disposable drug delivery device into which a patient or medical personnel must insert a drug cartridge prior to use.
Particularly in the case of patient-operated LVDs which require insertion of a drug cartridge prior to use, the drug delivery process from start to finish can be a complicated multi-step process, including gathering of all of the device components, assembly of the components to produce the LVD ready for drug administration and sterilization of the injection site before the actual process of injecting the drug can even begin. For example, the preparation step includes sourcing a sterilizing liquid and a sterilizing swab to apply the sterilizing liquid. The sterilizing liquid then needs to be applied over the intended injection site on a patient's body to ensure the injection site is fully sterilized, and the sterilizing materials then put aside or discarded before a medicament administration procedure can be commenced. Gathering all these materials and performing the sterilizing process is time-consuming and burdensome, and adds complication to the process for the patient. This renders the process intrusive upon his or her daily schedule, and increases the risk that the patient may not correctly perform the drug administration.
There are limitations as to the maximum volume of liquid medicament one injection site can accept within a predetermined amount of time without causing the patient discomfort, pain, inhibiting pharmacokinetics or causing leakage out of the injection site. To avoid complications of such interactions between the drug and the patient's body, such large-volume biological medicaments should not be administered at the same injection site on the patient's body twice or more in succession. Therefore, this is another factor in the medicament administration process which the patient must take into consideration.